i want to know what causes rasp in exhaust when you gear down, and how can you make it happen, for example i got a friend with a truck and dual 40 flows and his wont rasp like mine, i got a 80 flowmaster on mine, so please help

 

Those rasps are quiet backfires that you hear due to a loss of backpressure.

 

Its all in how you produce the gases. And ESPECIALLY on how you deliver. Adding clean air to your flow tubes is the same thing as putting too much water in your gravy. If ya can't hackit, grab ya jacket... make sure ya don't get dat fuuuunnnnnnyyyyyyyyy feelin!